Method of treating automobile exhaust gases



5 June 21, 1966 A. a. STILES 3,257,153

METHOD OF TREATING AUTGMOBILE EXHAUST GASES Filed Feb. 12, 1965 GasesContaining C 02 H O I Less NO M (V0 Gases Con1oining CuO' Cu C1 0 Leadcompounds not 9 3 2 l ud compounds deleterious to the not deleterious tocatalyst. the catalyst.

Mg(V0 CuO-CuCr O INVENTOR ALVIN B. STILES BY aw/( United States Patent3,257,163 METHOD OF TREATING AUTOMOBILE EXHAUST GASES Alvin B. Stiles,Welslrire, Wilmington, Del., assignor to E. I. du Pont de Nernours andCompany, Wilmington,

Del., a corporation of Delaware Filed Feb. 12, 1965, Ser. No. 438,817 2Claims. (Cl. 23-2) This application is a continuation-in-part of mycopending application U.S. Serial No. 193,899, filed May 4, 1962, andnow abandoned, which is in turn a continuation-in-part of applicationU.S. Serial No. 116,081, filed June 9, 1961, and now abandoned.

This invention relates to the treatment of automobile exhaust gaseswhich contain such products as nitrogen oxide, carbon monoxide, andhydrocarbons and products of combustion of alkyl lead antiknockcompounds. This invention is more particularly directed to the treatmentof such gases with both a catalyst and a lead scavenger as follows,

Scavenger:

Vanadium oxides, and vanadates of Alkali metals Alkaline earth metalsAluminum Copper Iron Cobalt Nickel Manganese Cerium Chromium Catalyst:

Mangano-chromia-manganite oxides, chromites, and

manganites -of Copper Iron Cobalt Nickel Cadmium Zinc Bismuth CeriumPlatinum Rhodium Palladium Ruthenium In the drawings:

FIGURE 1 illustrates an embodiment in which automobile exhaust gases arepassed first through :a scavenger and thereafter through a catalyst, and

FIGURE 2 represents a modification in which the scavenger is mixed withthe catalyst.

According to the present invention the catalysts above tabulated areprotected from the combustion products of alkyl lead and of the halogencompounds often included in leaded .gasolines. The scavengers listed canbe used for a preliminary treatment of the exhaust gases before theypass to the catalyst but it is not imperative that there be separatezones. Where the scavenger and catalyst are placed in separate zones orbeds, the exhaust gases are passed over both beds continuouslythroughout operation of the engine.

In FIGURE 1 there is illustrated a modification of the invention inwhich a typical scavenger, magnesium vanadate, is placed in the firstsection of a catalytic muffier. Gases must first pass through thisbefore reaching the second section which contains, illustratively,manganechromia-manganite.

Alternatively the magnesium vanadate pellets can be mixed with thecatalyst pellets in at least one or two sections of the mufller and asspecifically shown the first section contains the mixture while theremaining sections do not.

Exhaust gases can be mixed with extraneous air before entering themuffler in order to provide suflicient oxygen for complete combustion ofthe carbon monoxide and hydrocarbons. The air can be supplied by meansof a pump or venturi or any other conventional means.

The scavengers do not remove all lead components from the automobileexhaust gases and apparently considerable quantities -of lead compoundspass through the scavenger to the catalyst. However the scavengerslisted seem to remove or sequester most of the products of combustion ofthe lead compounds and the halogen compounds so that they have no eifecton the catalyst.

Scavengers The scavengers to be used are ammonium vanadate, vanadiumpentoxide, vanadium tetroxide, and the vanadates of:

Sodium Strontium Cobalt Potassium Magnesium Nickel Lithium AluminumManganese Calcium Copper Cerium Barium Iron Chromium It is to be notedthat in the above list the ammonium vanadate is converted at relativelylow temperature to vanadium oxides and is to be considered equivalent tovanadium pentoxide, vanadium tetroxide, and their mixtures.

The scavengers or mixtures of them can be utilized in any form in whichthey supply sufiicient surface to the gases being treated without at thesame time creating excessive resistance to gas flow. In general theproducts should be in the form of particles, pellets, granules, rods, orother appropriate shapes. Most preferred is to have particles in therange of about M to inch in largest cross section. While not usuallypreferred, the scavengers can be in the form of even smaller discreteparticles. Thus the scavengers either as such or preferably supported asbelow described can be used in the form of particles down to 25 micronsin largest dimension. Below this figure the particles are very apt tofuse to the catalyst surface and to become almost a part of thecatalyst.

It will often be found most advantageous to support the scavengers uponor to mix them with suit-able carriers because of the tendency of someof them to melt under the conditions of high temperature operationsometimes encountered in treatment of automobile exhaust gases. Thecompounds can be supported upon or mixed with any of the carriers listedbelow and additionally therev can be used inert materials which do notmelt at the temperatures reached and which do not decompose or react.Thus there can be used various clays such as bentonite, diatomaceousearth, finely divided silica, or silica aero gels.

Ordinarily from about 5 to 50% by Weight of an alkali metal or alkalineearth metal scavenger should be applied to a support. More or less canbe u-ed but if too little is used the activity and capacity drop and thevolume of the equipment required becomes unreasonable. Eighty or evennearly one hundred percent of the scavenger can be used on the carrier.The advantage of using a carrier to reduce fusion will be in part lostwith very large amounts of scavenger.

The catalysts to be used in conjunction with the scavengers mentionedwill be listed below by sections:

THE MANGANO-CHROMIA-MANGANITE CATALYSTS The manganoechromia-manganitecatalysts to be used according to the invention are described andclaimed as such'and with co-catalysts, interspersants, and supports incopending Howk and Stiles applications Serial No. 109,483, filed May 19,1961 and Serial No. 59,263, filed September 29, 1960, and reference canbe had to such applications for further details. A general descriptionshould be sufficient here.

The mangano-chromia-manganites have the following empirical chemicalcomposition:

XCr O 2YMnO in which n can be 2, 3, and 6 and m' can be 1, 1.33, 1.5, 2,and 2.5. The MnzCr Weight ratio can vary from 3:05 to 3:30. The atomicratio, that of YzX, is substantially the same and thus when Y equals 3,X can equal 0.5 to 30. A mangano-chromia-manganite can be preparedhaving a ratio of Mn:Cr of 3:2 according to methods of Lazier U.S.Patent 1,746,782 and 1,964,001 and Wortz U.S. Patent 2,108,156. In theseand other prior suggestions of manganese chromites it is proposed thatequimolecular amounts of the manganese compound and the chromiumcompound be used which in aqueous solutions results in a product havinga ratio of 3:2 because a third of the chromium is not precipitated andis washed away.

The mangano-chromia-manganites can be prepared by procedures which aredescribed in detail in the Howk and Stiles applications above mentioned.Generally, it can be said that they are prepared by reacting appropriatesalts of manganese and chromium in aqueous solution. Thus manganesenitrate and chromic acid anhydride are dissolved in water and ammonia isadded to make a precipitate. The products of high manganese ratio can beprepared by adjusting the amounts of components, but a high chromiumproduct can be made when a hexavalent chromium salt is used as achromium source only by adding further chromium compound, such asammonium ch-romate, to the precipitate thus prepared after filtration.Alternatively the appropriate proportion of suit-able salts such asmanganese nitrate with chromium nitrate can be precipitated or fusedtogether to give mangano-chromiamanganites of the desired Mn:Cr ratio.

(IO-CATALYST A co-catalyst can be included with themang-anochromia-manganite and there can be used, for example, suchco-catalysts as those described in Patent No. 1,964,- 001. Thus one ormore of the following can be added as the carbonate or can be added as abasic chromate or oxide:

copper cadmium nickel cobalt zinc tin iron 'bismuth The co-catalystscan, of course, be added as other compounds depending upon the specifictreatment and processing conditions used.

The weight ratio of co-cat'alyst: mangano-chromiamanganite can varygreatly and can range from, say, :1 to 1:10. About 1:1 is preferred.

INTERSPERSANTS It is often desirable to add an interspersant to thecatalyst aggregate as described in the above mentioned Howk and Stilesapplications. The interspersants are refractories which have a meltingpoint above 1000 C and more preferably above 1600 C. The crystallitesize .(1) Aluminum oxide and hydroxide (2) Titania (3) Thoria (4) Ceria4 (5) Chronu'a (6) Magnesia (7) Calcium oxide and hydroxide (8) Bariumoxide and hydroxide (9) Strontium oxide (10) Zinc oxide (11) Manganeseoxide (12) Silica (13) Beryllia (14) Zirconia (15) Lanthana (16) HafniaAluminum hydroxide, which is present as oxide in the final product, ispreferred. Manganese oxide and chromia are listed as interspersants tobe added in amounts ex ceeding those which would be present in themanganochromia-manganite of the ratios described.

It is to be noted that the interspersants can be added in the firstprecipitation or formation of the catalyst aggregate and a secondinterspersant can be added after the catalyst aggregate has been formedand especially after it has been heat-treated or calcined. Theinterspersants can be heat-decomposable products or they can beintroduced in the form of sols or dispersions.

The amount of the interspersants can be Widely varied and the total ofthe first interspersants can run from, say, 5 to 75% based upon theweight of mangano-chromiamanganite plus a co-catalyst if there is one. Asecond interspersant can range in amount from 0.5 up to 50% or even moreby weight of the weight of the catalyst aggregate to which it is added.

Further details of the introduction of co-catalysts and interspersantscan be found in the Howk and Stiles applications previously mentioned.

SUPPORTS Supports suitable for use according to the present inventioninclude various refractory bodies customarily used for this purpose inthe art. There can be used for example:

The preferred refractory supports are:

Bauxite Zirconia Titania Activated alumina It is preferred that thesurface area be at least 10 m.- g. with pore dimensions such that 40%are less than 200 Angstroms. It is even more preferred that the surfacearea be at least m. g. vwith pore dimensions of at least 60% less than200 Angstroms. Mangano-chromia-manganite catalysts employing suchpreferred supports are described and claimed in U.S. application SerialNo. 109,- 483, filed May 19, 1961. Thecatalyst support can be washedwith water or with weak acids followed by washing with water as coveredin a copending' application of the assignee of the present case, GilbyU.S. application Serial No. 108,763, filed May 9, 1961.

The amount of catalyst applied to a support can be Widely varied inaccordance with usual practices but ordinarily will run from 1 to about20% by weight based upon the Weight of refractory. -Less catalyst doesnot ordinarily give adequate activity and more catalyst is wasteful.

The catalyst containing the alkali metal vanadate or vanadium oxide,whether tableted or supported as described, can be calcined, if desired,at a temperature which does not go so high as to result in sintering ofthe catalyst components including the vanadium compound. Temperaturesfrom about 250 to 800 C. will be satisfactory and the times can run froma few minutes up to 30 minutes or an hour. Such calcination will beparticularly desirable if there are heat-decomposable components in thecatalyst.

THE OXIDE, CHROMITE. AND MANGANITE CATALYSTS The catalysts used for theinvention can be chromium oxide and oxides, chromates, and manganites ofcopper, iron, cobalt, nickel, cadmium, zinc, bismuth, and cerium andmixtures of these.

The oxides of the metals named can be in any stage of oxidation andafter the oxides are applied, or formed, in

7 catalysts of the invention the oxide will resonate from one valencestate to another. Ordinarily the oxides will be prepared in a catalystfor sale in the highest valence state because this is convenient.

The oxides will ordinarily be prepared by a reduction of a decomposablecompound. Thus copper nitrate, carbonate, acetate, formate, hydroxide,or the like can be heated to form the oxide. The same salts of the othermetals can similarly be used.

The chromites and manganites of the metals named can be formed byheating the basic metal chromate. The manganite can be formed bymetathesis or preferably by heating and decomposition such as by heatinga nitrate of the metal in the presence of suitable manganates such asammonium manganate. The preparation of catalysts will be illustratedfurther in the examples.

The co-catalysts and the interpersants described above can be used withthe oxide chromite and manganite cataly'sts in the proportions describedabove.

The catalysts, together with co-catalysts and interspersants if any, canbe pilled or tableted as can the mangano-chromia-manganite catalysts.Alternatively and preferably they will be supported upon a refractorysupport such as one of those listed above and in the proportions abovelisted.

PRECIOUS METAL CATALYSTS The precious metal catalysts used can beplatinum, rhodium, palladium, ruthenium and their mixtures, and with thecatalysts listed above.

The metals are usually applied as finely divided or colloidal metalsupon the surfaces of appropriate carriers. The preparation of suchcatalysts is conventional but will be illustrated hereinafter.

The refractory support can be used as a carrier and any of those listedabove is satisfactory. The amount of the precious metal to use upon .acarrier is well understood. Generally from about of 1% to 1% by Weightis used based upon the weight of carrier. More can of course be used butthis is expensive and if much less is used the activity is too low.

The amount of the scavengers to be used can be widely varied. If toolittle is used then they will become relatively ineffective after tooshort a time. If too much is used, too great a resistance to flow ofgases may become involved and the weight, volume, and cost of thematerial may become excessive. In general the ratio of the weight ofscavenger to the weight of catalyst including support will range from10:1 to 0.1 1. Generally about equal amounts by weight are preferred. Itis to be noted that when the catalyst particles are mixed with particlesof scavenger the mixture can extend throughout the catalytic bed or canbe confined to individual sections. As illustrated in the drawing onlythe first section contains the scavenger. The amount of scavengerillustrated in FIGURE 2 is intended to be approximately 1/ 12:1 for theratio of scavenger to catalyst.

In order that the invention may be better understood reference should behad to the following illustrative examples.

EXAMPLE 1 Preparation of the catalyst (l) 250 parts by weight ofactivated alumina, 4-8 mesh size, having a surface area of 200 squaremeters per gram and having of the pores less than 600 A. in diameter isimmersed in a solution consisting of 5 parts by Weight platinum aschloroplatinic acid in 500 parts by weight water at 50 C. for 15minutes.

(2) The granules, after draining, are placed in a tube which permitshydrogen to enter atone end and exhaust at the other. Hydrogenhumidified to 60% at 75 C. is passed over the catalyst for one hour at75 C. to reduce the metal and to control migration of the preciousmetals to a peripheral location on the granules.

(3) Th catalyst is finally heated to 200 C. in the same hydrogen flowfor one hour.

Preparation of the lead scavenger (4) 250 parts by Weight of activatedalumina, of the type used for the catalyst preparation above, isimmersed in a solution-slurry composed of 20 parts by weight magnesiumoxide as the nitrate and 117 parts by Weight ammonium metavanadate in500 parts by weight water at 90 C. for 10 minutes.

(5) The granules are drained, then calcined at 400 C. for one hour.

Use of lead scavenger and lead catalysts The catalyst and scavenger asprepared above are charged into a muffier-reactor as shown in FIGURE 1.The catalyst is placed in the 3 down-stream cells. The lead scavenger isplaced in equal weight in the 3 up-stream cells. The exhaust gases whenfirst contacting the lead scavenger are freed ofa portion of the leadwhich would otherwise poison and slowly deactivate the catalyst in thedown-stream cells. A large part of the lead is not absorbed by thescavenger'nor by the catalyst but this lead does not greatly affect thecatalyst.

Although the lead scavenger does not primarily function as a catalyst,it has appreciable activity for the oxidation and abatement of thenoxious components of automotive engine exhausts, particularly when thescavenger is comparatively new.

The scavenger and catalyst above described are also employed as shown inFIGURE 2 of the drawing. Equal parts by weight of the granules ofmagnesium metavanadate and of the platinum catalyst are mixed andcharged into the first section of the catalytic mufiler as illustratedin FIGURE 2. The remainder of the muffier is filled with the platinumcatalyst.

The exhaust gases from an internal combustion engine are mixed with airand introduced into the converter. The lead compounds contained in thegases are substantially removed as they pass through the first section.The exhaust gases are passed over both the scavenger section and thecatalyst section continuously throughout operation of the engine.

A similar catalytic muffler charge can be made by using the mixture ofgranules in two, three, or all of the sections.

A similar catalyst charge is prepared using the precious metal catalystdescribed but supporting the magnesium vanadate upon the activatedalumina as in Items 4 and 5 above such that most of the alumina is inthe range of 40-80 microns in largest dimensions.

This scavenger is used in a weight equal to the Weight of the catalystand is charged as shown in FIGURE 2 into one or more sections of themufiler.

EXAMPLE 2 Preparation of the catalyst (1) 250 parts by weight ofsilica-alumina, 88% SiO 12% A1 4 8 mesh, having 40 square meters pergram surface area and 50% of the pores smaller than 400 A. in diameteris immersed in a solution composed of 5 parts by weight palladium aspalladium chloride in 500 parts 'by weight water at 40 C. for minutes.

(2) The granules, after draining, are placed in a closed tube andhydrogen humidified to 50% at 70 C. is passed over the catalyst for onehour, then the temperature is increased to 250 C. for an additionalhour.

Preparation of the scavenger (3) 250 parts by weight of silica-alumina,48 mesh, of the type used in the preparation above is immersed in asolution-slurry composed of 170 parts by weight ammonium inetavanadatein 500 parts by weight water at 90 C. for 10 minutes.

(4) The granules are drained, then are calcined at 400 C. to convert theammonium vanadate to V 0 Use of the scavenger and catalyst The catalystas prepared above is placed in the last three cells and the scavenger inequal weight is placed in the first three cells of the reactor-mufflershown in FIGURE 1. Exhaust gases are passed over both the scavenger andthe catalyst continuously throughout the operation of the engine towhich such a reactor-muffler is attached.

The scavenger and catalyst particles are intermixed in equal parts byweight and charged into the first cell of a mufiier as shown in FIGURE2. The mixture can be placed in two, three, or all of the cells.

The catalyst granules can be mixed with a lead scavenger in more finelydivided form. Thus the scavenger as prepared in Items 3 and 4 above canbe supported upon pulverized diatomaceous earth having a particle sizein the range of 25-70 microns.

EXAMPLE 3 Catalytic mufilers are charged as shown in FIGURES 1 and 2,and as described in Example 2 but replacing palladium with an equalweight of ruthenium.

EXAMPLE 4 Catalytic mufllers are charged as shown in FIGURES 1 and 2,and as described in Example 2 but replacing palladium with an equalweight of a 50-50 mixture of platinum and rhodium.

EXAMPLE 5 Catalytic mufilers are charged as shown in FIGURES 1 and 2,and as described in-Example 2 but replacing palladium by an equal weightof a 50-50 mixture of palladium and rhodium.

EXAMPLE 6 Catalytic mufflers are charged as shown in FIGURES 1 and 2,and as described in Example 2 but replacing palladium with an equalweight of a 5050 mixture of platinum and palladium.

EXAMPLE 7 (2) A concentrated solution of ammonium carbonate is slowlyadded to the solution prepared in Step 1 to cause complete precipitationas indicated by a test of the supernatant liquid.

(3) The precipitate is filtered, then calcined at 400 C. for one hour.

(4) The calcined powder is kneaded in a machine of the type used in thebakery industry in proportion such that parts by weight of the powderobtained in Item 3 above and 40 parts by weight of magnesium oxide asthe acetate and water are mixed tomake a uniform thick paste.

(5) The kneaded paste is calcined at 450 C. for one hour.

(6) The calcined paste is divided into three equal parts. The first partisgranulated and screened to 814 mesh, the second part is mixed with apilling lubricant and pilled in a pharmaceutical machine to form /s xcylinders, whereas the third part is extruded as a moist paste toproduce 45" x /s cylinders.

Preparation of the scavenger (7) 250 parts by weight of activatedbauxite, 4-8 mesh, having a surface area of square meters per gram andhaving pores such that 75% are less than 600 A. in diameter is immersedin' a solution-slurry of 100 parts by weight of sodium metavanadate in500 parts by weight water at 75 C. for 10 minutes.

(8) The impregnated granules are dried at 175 C. for 1 hour.

Use of the scavenger and catalyst The scavenger is charged to the firstthree cells and an equal weight of catalyst is charged to the last threecells in FIGURE 1. Exhaust gases are passed over both the scavenger andthe catalyst continuously throughout the operation of an engine to whichsuch a mufilerreactor is attached.

The scavenger and catalyst particles are intermixed in equal parts byweight and charged into the first cell of a muffler as shown in FIGURE2. The mixture can be placed in two, three, or all of the cells.

The catalyst granules can be mixed with the lead scavenger in morefinely divided form. Thus the scavenger as prepared in Items 5, 6 and 7above can be supported upon finely pulverized and porous silica-alumina,325 mesh, that is it passes ISO-and is retained on 325.

EXAMPLE 8 Preparation of the catalyst (1) A solution-slurry is preparedcomposed of 59 parts by Weight of nickel as the nitrate and 100 parts byWeight CrO in 1,000 parts by weight of water at 45 C. together with 40parts by weight of pigment-grade titanium dioxide.

(2) A concentrated solution of ammonium carbonate is slowly added to thesolution-slurry of paragraph one to' effect complete precipitation asdetermined by a test of the supernatant liquid.

(3) The precipitate is filtered, then is calcined at 400 C. for onehour.

(4) The powder obtained from Item 3 is kneaded in such a way that 100parts by weight of the powder and 16.4 parts by weight of Ce O as thenitrate are charged to a kneading machine together with sufficient waterto form a uniform thick paste.

(5) The paste is dried and calcined at 400 C. for one hour.

(6) The calcined paste is converted to pills having A; x M; dimensionsas right cylinders.

(7) The pills are heat treated at 500 C. for three hours.

Preparation of the scavenger (8) 250 parts by weight of silica-aluminain the form of A" x /s" cylinders and having a surface area of 40 squaremeters per gram and having 50% of the pores less than 400 A. in diameteris immersed in a solutionslurry composed of 9 parts by weight of Al asthe nitrate and 117 parts by weight of ammonium metavanadate and 50parts by weight water at 90 C.

(9) The impregnated cylinders are drained, then calcined at 300 C. forone hour.

Use of the scavenger and catalyst The scavenger as above prepared ischarged to the first of ten equal cells in a muffier-reactor. Thecatalyst is charged to the down stream 9 equal cells so that the weightrelationship between the scavenger and catalyst is 1 to 9.

The scavenger and catalyst can also be mixed and used as shown in FIGURE2 of the drawings. Equal parts by weight of the catalyst and scavengercan be charged to the first section as illustrated in FIGURE 2 withcatalyst in the remaining section. Instead the mixture can be used intwo, three, or even more of the sections.

A similar catalyst charge can be prepared using the scavenger in veryfinely divided form. Thus equal parts by weight can be charged into one,two, three or more cells of a mixture into which the scavenger issupported upon activated alumina, 150-325 mesh.

EXAMPLE 9 Catalytic mufiiers are charged as described in Example 8 withthe exception that 59 parts by weight of cobalt replaces the nickel ofItem 1.

EXAMPLE 10 Catalytic mufilers are charged as described in Example 8 withthe exception that 113 parts by weight of cadmium replacesthe nickelspecified in Item 1.

EXAMPLE l1 Catalytic mufiiers are charged as described in Example 8 withthe exception that 65 parts by weight of zinc replaces the nickel. V 4

EXAMPLE 12 Catalytic mufflers are charged as described in Example.

8 with the exception that 56' parts by weight of iron replaces thenickel.

EXAMPLE 13 Catalytic mufilers are charged as described in Example 8 withthe exception that 140 parts by weight of bismuth replaces the nickel.

EXAMPLE 14 Catalytic mufiiers are charged as described in Example 8 withthe exception that 55 parts by weight of tin replaces the nickel.

EXAMPLE 15 Catalytic mufiiers are charged as described in Example 8 withthe exception that 32 parts by weight of copper replaces one-half of thenickel.

EXAMPLE 16 Preparation of the catalyst (1)A solution-slurry is preparedcomposed of 2.75 parts by weight manganese, 3.2 parts by weight copper,3.0 parts by weight nickel, and 31.2 parts by weight chromium, all asthe nitrates, together with 20 parts by weightalumina as finely dividedhydrate of the type used in Step 1 of Example 7 in 100 parts by weightwater at 60 C.

(2) A concentrated aqueous solution of ammonium 10 (5 The paste iscalcined at 350 C. for one hour. (6) The ignited paste is formed into 4:x cylinders..

Preparation of the scavenger Use 0 the scavenger and catalyst Thescavenger and catalyst as thus prepared are charged as in FIGURE 1.

The scavenger and catalyst particles can instead be intermixed in equalparts by weight and charged in the first cell of a mufller as shown inFIGURE 2. The

mixture can be placed in two, three, or all of the cells.

The catalyst can be mixed with the lead scavenger in more finely dividedform. Thus the catalyst as prepared in Items 7 and 8 can be supportedupon diatomaceous earth having particle size 150-325 mesh.

EXAMPLE 17 (1) 250 parts by weight, 4-8 mesh, activated alumina of thetype used in Example 1 is immersed in a solution composed of 30 parts byweight cobalt and 6.9 parts by weight zirconium dioxide, both asnitrates, in 500 parts by weight water at 80 C.

(2) The impregnated alumina is drained, then calcined at 400 C. for onehour.

Preparation of the scavenger (3) 250 parts by weight of 48 mesh granularsilica alumina having a surface area of 40 square meters per gram andhaving of the pores smaller than 400 A. in diameter is immersed in asolution-slurry composed of 117 parts by weight ammonium metavanadateand 25 parts by weight titanium dioxide as a colloidal dispersion in 500parts by Weight water at 90 C. for 10 minutes.

(4) The impregnated granules aredrained, then calcined at 300 C.

A Use of the scavenger and catalyst The scavenger and catalyst as aboveprepared are charged as shown in FIGURE 1.

The scavenger and catalyst particles can instead be I intermixed inequal parts by weight and charged into the first cell'of the mufiier asshown in FIGURE 2. The mixture can be placed in two, three, or all ofthe cells.

The catalyst granules can be mixed with the lead scavenger in morefinely divided form. Thus the scavenger as prepared in Item 3 and 4above can be supported upon-pulverized silica gel, particle size 30-80microns.

EXAMPLE l8 Catalytic mufilers are charged as shown in FIGURES 1 and 2and as just described in Example 17 but with 32 parts by weight ofcopper as the nitrate used together with the ammonium metavanadate inStep 3.

EXAMPLE 19 Catalytic mufllers are charged as shown in FIGURES 1 and 2and just as described in Example 17 except that 9 parts by weight ofaluminum as the nitrate is used together with the ammonium metavanadatein Step 3.

EXAMPLE 20' Catalytic mufiiers are charged as shown in FIGURES 1 and 2and just as described in Example 17 with the exception that 30 parts byweight of cobalt as the nitrate is used together with the ammoniummetavanadate in Step 3.

1 1 EXAMPLE 21 Catalytic mufiiers are charged as shown in FIGURES 1 and2 and as described in Example 17 with the exception that parts by weightof nickel as the nitrate is used together with the ammonium metavanadatein Step 3.

EXAMPLE 22 Catalytic mufiiers are charged as shown in FIGURES I 1 and 2and as just described in Example 17 except that parts by weight ofcerium as the nitrate is used together with the ammonium metavanadate inStep 3.

EXAMPLE 23 Catalytic mufliers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the exception that 17 parts byweight of chromium as the nitrate is used together with the ammoniummetavanadate in Step 3.

EXAMPLE 24 Catalytic mufiiers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the exception that 166 parts byweight of Na PO replaces the ammonium metavanadate in Step 3.

EXAMPLE 25 Catalytic muffiers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the ex-' ception that 150 parts byweight of K HPO is used instead of the ammonium metavanadate in Step 3.

EXAMPLE 26 Catalytic mufflers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the exception that 174 parts byWeight of K 80 is substituted for the ammonium metavanadate in Step 3.

EXAMPLE 27 Catalytic mufilers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the eX- ception that 142 parts byweight of Na SO is substituted for the ammonium metavanadate in Step 3.

EXAMPLE 28 Catalytic muffiers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the exception that 135 parts byweight of Ni (PO is substituted for the ammonium metavanadate in Step 3.

EXAMPLE 29 Catalytic mufliers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the exception that 150 parts byweight of NiSO is substituted for ammonium metavanadate in Step 3.

EXAMPLE 3O Catalytic mufiiers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the exception that 121 parts byweight of NaVO is substituted for the ammonium metavanadate in Step 3.

EXAMPLE 31 Catalytic mufllers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the exception that 138 .parts byweight of KVO is substituted for the ammonium metavanadate in Step 3.

EXAMPLE 32 Catalytic muffiers are charged as shown in FIGURES 1 and 2and as described in Example 17 with the exception that 130 parts byweight of Mg(VO is substituted for the ammonium metavanadate in Step 3.

12 EXAMPLE 33 Preparation of the catalyst (3) 250 parts by weight of 4-8mesh activated alumina of the type used in Example 1 is immersed in asolutionslurry of 68 parts by weight of barium as the nitrate and 117parts by weight of ammonium metavanadate in 500 parts by weight Water at90 C. for 10 minutes.

(4) The granules are drained, then calcined at 350 C. for one hour.

Use of the scavenger and catalyst The scavenger and catalyst as thusprepared are charged to a muffler-reactor as shown in FIGURE 1.

The scavenger and catalyst particles can instead be intermixed in equalparts by weight and charged into the first cell of a mufiier-reactor asshown in FIGURE 2. The mixture can be placed in two, three, or all ofthe cells.

The catalyst granules can be mixed With the lead scavenger in morefinely divided form. Thus the scavenger as prepared in Items 3 and 4above can be supported upon pulverized activated alumina, -170 mesh.

EXAMPLE 34 Catalytic mufflers are charged as shown in FIGURES 1 and 2and as just described in Example 33 except that 59 parts by weight ofnickel replaces the copper in Item 1.

EXAMPLE 35 Catalytic mufliers are charged as shown in FIGURES 1 and 2and as just described in Example 33 except that 56 parts by weight ofiron as the nitrate replaces the copper. 1

EXAMPLE 36 Catalytic mufflers are charged as shown in FIGURES 1 and 2and as just described in Example 33 except that 59 parts by weight ofcobalt as the nitrate replaces the copper.

EXAMPLE 37 Catalytic mufilers are charged as shown in FIGURES 1 and 2and as just described in Example 33 except that 113 parts by weight ofcadmium as the nitrate replaces the copper.

EXAMPLE 38 Catalytic mufilers are charged as shown in FIGURES 1 and 2and as just described in Example 33 except that 65 parts by weight zincas the nitrate replaces the copper.

EXAMPLE 39 Catalytic r'nutfiers are charged as shown in FIGURES 1 and 2and as just described in Example 33 except that parts by weight ofbismuth as the nitrate replaces the copper.

EXAMPLE 40 Catalytic mufflers are charged as shown in FIGURES 1 and 2and as just described in Example 33 except that 70 parts by weight ofcerium as the nitrate replaces the copper.

EXAMPLE 41 Preparation of the catalyst 1) 250 parts by weight of 4-8mesh activated alumina of the type used in Example 1 is immersed in asolution Preparation of the lead scavenger (3) 250 parts by weight of8-14 mesh activated alumina of the type usedyin Example 1 is immersed ina solution-slurry composed of 30 parts by weight of nickel as thenitrate and 117 parts by weight of ammonium metavanadate in 500 parts byweight water at 90 C. for 10 minutes.

(4) The impregnated granules are drained, then calcined at 350 C. forone hour.

Use of the scavenger The scavenger as thus prepared is charged to theupstream 9 cells of a mufller reactor compartmented into 10 cells havingequal volume. The catalyst was charged to the remaining down-streamcell.

The catalyst and scavenger can be mixed as generally described above andcan be charged to a catalytic mufiler of the type shown in FIGURE 2.

The lead scavenger in more finely divided form can be I applied to thecatalyst granules. Thus the scavenger as prepared above can be supportedupon activated bauxite,

. 150-325 mesh, and mixed in equal proportions by weight with thecatalyst granules. The mixture can be charged as in FIGURE 2 to one,two, three or more of the cells and can be charged to all of them usingmore or less of the scavenger.

EXAMPLE 42 Catalytic mufiiers are charged as described in Example 41except that 30 parts by weight of nickel is used to replace the cobaltspecified in Step 1.

EXAMPLE 43 Catalytic mufflers are charged as described in Example 41except that 32 parts by weight of copper replaces the cobalt in Step 1.

EXAMPLE 44 Catalytic mufiiers are charged as described in Example 41except that 28 parts by weight of iron replaces the cobalt in Step 1.

EXAMPLE 45 Catalytic mufflers are charged as described in Example 41except that 33 parts by weight of zinc replaces the cobalt in Step 1.

14 EXAMPLE 46 Catalytic mufiiers are charged as described in Example 41except that 34 parts by weight of cerium replaces the cobalt in Step 1.

. EXAMPLE -47 Catalytic mufflers are charged as described in Example 41except that 51 parts by weight of bismuth replaces the cobalt in Step 1.

I claim:

1. In a process for treatment of automobile exhaust gases produced byburning leaded gasoline the steps comprising adding air to said gasesand passing them continuously throughout operation of the automobileinto contact with a scavenger selected from the group consisting of thevanadates of alkali metals, alkaline earth metals, aluminum, copper,iron, cobalt, nickel, manganese, cerium, and chromium and a catalystselected from the group consisting of mangano-chromia-manganite; oxides,chromites, manganites of copper, iron, cobalt, nickel, cadmium, zinc,bismuth and cerium; and precious metal catalysts selected from the groupconsisting of platinum, rhodium, palladium and ruthenium.

2. In a process for treatment of automobile exhaust gases produced. byburning leaded gasoline the steps comprising adding air to said gasesand passing them continuously throughout op'eration of the automobilefirst into contact with a scavenger selected from the group consistingof the vanadates of alkali metals, alkaline earth metals, aluminum,copper, iron, cobalt, nickel, manganese, cerium and chromium andthereafter into contact with a catalyst selected from the groupconsisting of manganochromia-manganite; oxides, chromites, manganites ofcopper, iron, cobalt, nickel, cadmium, zinc, bismuth and cerium; and.precious metal catalysts selected from the group consisting of platinum,rhodium, palladium and ruthenium.

References Cited by the Examiner UNITED STATES PATENTS 3,025,133 3/1962Robinson et a1 232 FOREIGN PATENTS 413,744 7/1934 Great Britain.

BENJAMIN-HENKIN, Primary Examiner. MAURICE A. BRINDISI, Examiner. E. C.THOMAS, Assistant Examiner.

1. IN A PROCESS FOR TREATMENT OF AUTOMOBILE EXHAUST GASES PRODUCED BYBURNING LEADED GASOLINE THE STEPS COMPRISING ADDING AIR TO SAID GASESAND PASSING THEM CONTINUOUSLY THROUGHOUT OPERATION OF THE AUTOMOBILEINTO CONTACT WITH A SCAVENGER SELECRED FROM THE GROUP CONSISTING OF THEVANADATES OF ALKALI METALS, ALKALINE EARTH METALS, ALUMINUN, COPPER,IRON, COBALT, NICKEL, MANGANESE, CERIUM, AND CHROMIUM AND A CATALYSTSELECTED FROM THE GROUP CONSISTING OF MANGANO-CHROMIA-MANGANITE; OXIDES,CHROMITES, MANGANITES OF COPPER, IRON, COBALT, NICKEL, CADMIUM, ZINC,BISMUTH AND CERIUM; AND PRECIOUS METAL CATALYSTS SELECTED FROM THE GROUPCONSISTING OF PLATINUM, RHODIUM, PALLADIUM AND RUTHENIUM.